Since we've been discussing public housing density, here is some research from the Growler plus a few calculations:
Arlington County: 0 public housing units (only Section 8 vouchers and set-asides)
Loudoun County: 0 public housing units
Prince William County, Manassas, and Manassas Park: 0 public housing units
The only jurisdictions with public housing are:
City of Alexandria: 1,150 public housing units
Fairfax County (including Falls Church and Herndon): 1,063 public housing units
Fairfax County covers 395 square miles and had a population of 969,749 according to the 2000 Census. Public housing density across the County is therefore 2.7 units per square mile. There is roughly one public housing unit for every 1,000 residents.
The City of Alexandria covers 15.75 square miles and had a population of 128,283 according to the 2000 Census. Public housing density is 73 units per square mile and roughly one public housing unit for every 111 residents.
Feel free to correct the Growler's math ...